The invention relates to a device for borderless printing of images by means of an ink jet printer, where the image-receiving material (also referred to as imaging material) lies against a support surface during the printing process, i.e., during the phase where the printing ink is applied to the imaging material.
In principle, ink jet printers belong to the known state of the art. However, the known ink jet printers have a persistent problem in printing images of photographic quality all the way to the edge of the material without spraying ink beyond the edge. The printing ink sprayed outside the edge contaminates the support surface on which the image-receiving material is positioned, so that the ink on the support surface smears the next following piece of material.
It is therefore the objective of the present invention to propose a device that allows an image to be printed all the way to the edge of the material without the aforementioned drawback of contaminating the support surface.
The present invention provides a device for borderless printing of images with an ink jet printer that has a support surface backing up the image-receiving material while printing ink is being applied to it. To meet the foregoing objective, the support surface of the device according to the invention is provided with cutouts. At least portions of the support surface are superficially hydrophobic, or the support surface consists of a hydrophobic material and/or is superficially oil-repellant or consists of an oil-repellant material, with the result that the support surface repels printing inks.
It is a particular advantage of the present invention that it is effective in preventing the contamination of the support surface, because the support surface is repellant to printing ink, so that the latter can no longer adhere to the support surface. Furthermore, the support surface has cutouts through which a major portion of the ink escapes directly, without coming into contact with the support surface. This is conducive to a better quality of the printed materials and fewer rejects.
The invention can be advantageously employed in ink jet printers that work with rollers, belts, or print stages.
According to an advantageous embodiment of the invention, the support surface is superficially hydrophobic, e.g., by having a hydrophobic coating, or the support surface itself consists of a hydrophobic material. This embodiment of the invention has the advantage that the printing ink cannot adhere to the support surface and is therefore easy to remove if the ink is water-based. If the ink is oil-based, it would be advantageous for the support surface to be oil-repellant.
The aforementioned cutouts are advantageously made large enough so that the ink that is sprayed outside the edge of the imaging material falls directly into the cutouts instead of on the support surface. It is advantageous if the cutouts surround the entire sheet that is being printed. In this case, the ink does not even have an opportunity to adhere to the support surface but escapes directly through the cutouts.
It is particularly advantageous if the cutouts are configured as slots that are appropriately arranged for the different formats of the imaging material, so that the edges of the imaging material lie on the slots. With this design concept for the support surface, if ink is sprayed outside the edge of the imaging material, it can run off directly through the slots, so that a contamination of the support surface is prevented.
To facilitate the disposal of the ink escaping though the slots, a further developed preferred embodiment of the invention has a vacuuming-, cleaning- or rinsing device arranged at the slots.
The slots in the support surface can also be designed in such a manner that the entire support surface forms a grate. This has the particular advantage that only a very small part of the printing ink falls on the grate and that the edges of the imaging material do not have to be positioned exactly over the slots. Most of the over-sprayed ink falls directly to a level below the grate, from which it can be carried away.
As an advantageous further development of the invention, if the grate has a hydrophobic or oil-repellant surface or is made of a hydrophobic or oil-repellant material, it will be particularly effective in avoiding the contamination of the support surface.
To ensure the safe capture and disposal of the printing ink falling through the grate, a preferred embodiment of the invention is equipped with a collecting and catching device to carry the ink away.
The vacuum device for removing the printing ink can simultaneously be used to provide suction for holding the imaging material in place on the support surface, so that a separate suction-generating device can be omitted.
To hold the imaging material in place, the support surface has small suction holes in addition to the cutouts, with the cutouts being larger than the suction holes.
To ensure a fast and easy removal of the printing ink from the ink-repellant surface, a preferred embodiment of the invention has an ink-removing device arranged at the support surface. The ink-removing device or cleaning device can be designed to be moved over the support surface, for example a roller with absorbent material such as fleece. It can also be advantageous if the support surface is moved along a cleaning device, especially in embodiments that use a movable support surface for the printing process. The cleaning device is preferably configured as a vacuuming-, wiping-, or similar device.
The vacuuming or wiping device advantageously consists of a washing bath at the underside of the roller or the belt and could be supplemented by a wiper or a cleaning roller. Thus, ink residues on the support surface can be removed in a simple manner without the need to use expensive techniques.